1. Field of the Invention
The invention relates generally to the field of security and specifically to the field of audio-video security recording for security purposes. More particularly, the present invention relates to performing audio and video compression and storing data in a local storage that is networked.
2. Description of the Background Art
Existing security systems for homes and commercial properties feature multiple video camera connected to a security box as shown in FIG. 1. The security box contains electronics to convert analog video and optional audio inputs to digital and performs audio and video compression by a System-On-Chip (SoC) processor, which then stores the results on a hard disk. The system could be programmed for continuous recording in a loop, recording upon a trigger caused by external alarm and scene change threshold, or timed scheduled recording. The cameras are connected by cabling and video is transmitted as analog to the main system. Such cabling makes it difficult to install the multiple camera inside and outside a residence or commercial because of routing of such long cabling between a user accessible box and cameras. Such a system provides 240 frames-per-second capture, which is divided by multiple cameras. For a 8-camera system, each camera video is captured at 240/8, or 30 fps, but capture resolution is usually low at CIF resolution (350×240). Such a security box can display captured video live from cameras or from hard disk on a monitor or TV, and user functions are controlled by front-panel buttons or an infrared remote-control unit (RCU). This means such a security box must be located near a TV and be visible for RCU operation. Such a system also provides means for remote viewing over internet, and can also send email messages with some snap shots of video when a alarm trigger occurs. However, there are many vulnerabilities in such a system. If internet is not working at the time of intrusion because phone or internet cables are externally cut, then no such email could be send. Thief can easily remove or damage the whole security box which removes all security data.
Another existing video security systems use networked security based where multiple camera units are connected to a PC or laptop computer over local area network or wide-area network, as shown in FIG. 2. For example, 9 wireless camera units can connect to a PC computer using Ethernet wires or 802.11 wireless communication. Each camera unit contains video camera, video compression, and network interface in this case. Existing systems use JPEG or MPEG-2 or MPEG-4 systems, but in the future this will probably extend to advanced H.264 video compression standard as well in new designs. If there is no local computer, it is also possible to connect the cameras to a router connected to a WAN gateway, so that multiple security video channels could be streamed to a remote PC or laptop. The remote PC or laptop could perform remote viewing or recording of one or multiple channels on its hard disk storage. One of the disadvantage of such a security system is that if internet access deliberately interrupted at the time of a security event, then it is not possible to stream the data for the event to the remote PC for recording. If the PC is located locally, then it could easily be removed by the perpetrators. Furthermore, such a system requires continuous stream of multiple video streams over local and wide area networks, which places a considerably load on such networks, thus causing unreliable operations and slowing other network activity. Cabled systems using Ethernet cabling also require difficult cabling of multiple camera units. Units configured to use 802.11 g systems contend bandwidth collisions with other systems, cordless phone, wireless microwaves, and other wireless communication systems on a limited number of channels. Thus, it becomes difficult and unreliable to transfer plurality of live compressed video stream in real-time without interruptions.